The existing techniques to enhance the absorption rate of an absorbent resin mostly involve reducing the particle size of the resin, granulating the resin during preparation, or forming micro-pores inside or on the outer surface of the resin using a foaming agent, in order to increase the surface area of the absorbent resin.
More specifically, the methods of forming micro-pores in the absorbent resin include using a liquid carbonate to prepare a foamed resin; performing UV polymerization in the presence of a carbonate to provide porosity; or dispersing an inert gas into a viscous monomer mixture and polymerizing the monomer mixture alone or in combination with an organic solvent having a low boiling point. These methods, however, have some disadvantages, such as difficulty in forming uniform pores in the absorbent resin, with a limitation to enhance the absorption rate, or possible deterioration of the physical strength of the absorbent resin, leaving fine powder. The formation of fine powder causes a need for conducting an additional process of removing the fine powder. In worse cases, the fine powder remaining without being eliminated can be introduced into sanitary materials or other finished products to spoil the working environment with loose powder grains or cause a release of tiny powder grains out of the finished products.
On the other hand, there has been studied on a method for forming an ionic bond between an absorbent resin and an ionic compound in order to enhance the absorbency of the absorbent resin. But, this conventional method also faces a limitation in enhancing the absorbency of the absorbent resin.
Such problems with the conventional techniques have led to a consistent demand for a method more effective in enhancing the absorption rate of the absorbent resin as well as absorbency.